The invention relates to a procedure for the preparation of vegetable pulp destined for juice and puree extraction, and a device for the enacting of the said procedure.
At present the work cycle for vegetable pulps in order to prepare them for the extraction of their juice and puree is normally constituted by the trituration of the fruit followed by heating, with the aim of making the successive separation of the useful part from the scrap easier.
Indeed, raising the temperature induces in the pulp a loss of consistency, a tendency to peel and a greater ease of detachment from the skin, which helps greatly in the passage of the puree through the holes of the sieve of the strainer which performs the separation.
Heating the triturate containing all of the parts of the fruit causes, however, drawbacks of an operative nature, such as blocking and consequent imperfect functioning of the heat exchangers and of the accessory organs, such as the pump and the valves, which have to be frequently halted for cleaning operations, as well as drawbacks due to a qualitative drop in the product itself, thanks to substances both natural and deriving from the chemical treatment of the fruit, which, with the increase in temperature, pass through the sieve as puree rather than being eliminated with the scrap (elements such as skins, stalks, seeds, stones etc).
This important negative aspect of the procedure using heat leads to processes which eliminate the heating of the fruit during this phase, but preparation solely by trituration, on the other hand, runs into considerable difficulties if heat is not applied and the operation is therefore done at room temperature.
In the case of large and dishomogeneous trituration, if the separation is made through relatively small holes, the complete extraction of the puree is not achieved, and a successive treatment of the scrap becomes necessary in order to recuperate the pulp still adhering to the said scrap, while if the separation is performed using sieves with larger holes the degree of extraction improves, but the puree has to undergo further treatment since it is mixed with scrap fragments which must be eliminated.
In the case of very small trituration, the degree of extraction even when working with small holes is greater, but the product quality suffers because of the high percentage of fragments in it, deriving from the fragmentation of the scrap due to the very fast action of the trituration.
In any case, therefore, extraction of the puree at room temperature, since it lacks the necessary "softening" of the pulp, is to be considered an unsatisfactory solution, born of a compromise between quantitative efficiency, product quality and operative simplicity, all of which objectives are difficult to achieve all together if the separation is to be done using prior art means and without heating.